{
  "bibcode": "2016GCN.19058....1B",
  "body": "J. Bolmer (MPE Garching), D. A. Kann (TLS Tautenburg), T. Kruehler,\nand J. Greiner (both MPE Garching) report on behalf of the GROND team:\n\nWe observed the field of GRB 160223A (Swift trigger 675361; Markwardt et\nal., GCN #19057) simultaneously in g'r'i'z'JHK with GROND (Greiner\net al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the\nESO La Silla Observatory (Chile).\n\nObservations started at 03:30:41 UT on 2016-02-23, 106 min after the GRB\ntrigger. They were performed at an average seeing of 1\".2 and at an\naverage airmass of 1.3.\n\nWe find a bright, uncatalogued point source within the Swift-BAT error\ncircle at\n\nRA (J2000.0) = 09:50:23.34\nDec. (J2000.0) = +09:22:09.0\n\nwith an uncertainty of 0\".5 in each coordinate.\n\nBased on the first 4.4 min of total exposure in g'r'i'z' and 4.0 min\nin JHK at a mid-time of 03:34:13 UT, we derive the following preliminary\nmagnitudes (all in AB system):\n\ng = 17.8 +- 0.1 mag\nr = 16.9 +- 0.1 mag\ni = 16.5 +- 0.1 mag\nz = 16.2 +- 0.1 mag\nJ = 16.1 +- 0.1 mag\nH = 15.9 +- 0.1 mag\nK = 15.8 +- 0.1 mag\n\nThe object fades by 0.4 mag until 04:55 UT on 2016-02-23, so we\npropose this source to be the optical/NIR afterglow of GRB 160223A.\n\nGiven magnitudes are calibrated against SDSS as well as 2MASS\nfield stars and are not corrected for the expected Galactic foreground\nextinction corresponding to a reddening of E_(B-V) = 0.03 mag in the\ndirection of the burst (Schlafly & Finkbeiner 2011).\n\n[GCN OPS NOTE(23feb16):  Per author's request, DAK was added to the author list.]",
  "circularId": 19058,
  "createdOn": 1456211933000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 160223A: GROND optical/NIR afterglow",
  "submitter": "Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 160223A"
}